A VALIDATED RP-HPLC METHOD FOR THE DETERMINATION OF MELATONIN AND ZOLPIDEM TARTARATE IN BULK AND PHARMACEUTICAL DOSAGE FORMS

Abstract

A new method was established for simultaneous estimation of Melatonin and Zolpidem Tartarate and by RP-HPLC method. The chromatographic conditions were successfully developed for the separation of Melatonin and Zolpidem Tartarate by using Hypersil BDS C18 column (250×4.6mm) 5.0µm, flow rate was 1.0ml/min, mobile phase ratio was (50:50 v/v) Potassium dihydrogen o-phosphate Buffer: Acetonitrite pH 4.3 (pH was adjusted with Ortho-phosphoric acid), detection wavelength was 235nm. The instrument used was WATERS HPLC Auto Sampler, Separation module 2690, photo diode array detector 996, Empower-software version-2. The retention times of Melatonin 2.60 mins and Zolpidem were found to be 3.31 mins. The % purity of Melatonin and Zolpidem Tartarate and was found to be 99.66% and 99.94% respectively. The system suitability parameters for Melatonin and Zolpidem Tartarate such as theoretical plates and tailing factor were found to be 3817 and 1.3, 4492, 1.1 and the resolution was found to be 6.0. The analytical method was validated according to ICH guidelines (ICH, Q2 (R1)). The linearity study Melatonin and Zolpidem Tartarate was found in concentration range of 12µg-72µg and 20µg-120µg and correlation coefficient (r²) was found to be 0.999 and 0.999, % recovery was found to be 95.0% and 105.0%, %RSD for repeatability was 0.095 and 0.087, % RSD for intermediate precision was 0.095 and 0.087 respectively. The precision study was precise, robust, and repeatable. LOD value was 0.7729 and 1.947 , and LOQ value was 2.3422 and 5.9026 respectively. Hence the suggested RP-HPLC.